The present invention relates to a hybrid drivetrain, having an internal combustion engine which is designed for a maximum internal combustion engine rotational speed; a dual-clutch arrangement which has a first friction clutch and a second friction clutch, wherein the friction clutches have a common input element, coupled to the internal combustion engine, and in each case one output element; a transmission arrangement which has a first sub-transmission and a second sub-transmission, wherein the output element of the first friction clutch is connected to an input of the first sub-transmission, and wherein the output element of the second friction clutch is connected to an input of the second sub-transmission; an electric machine which is or can be connected to the output element of the second friction clutch via a machine transmission ratio, in such a way that a purely electric driving mode can be established via the second sub-transmission, wherein the electric machine is designed for a maximum machine rotational speed.
In addition, the present invention relates to a method for operating such a hybrid drivetrain.
Such a hybrid drivetrain is suitable, in particular, for use in motor vehicles such as passenger cars. The drivetrain has a dual-clutch transmission with the abovementioned dual-clutch arrangement and the abovementioned transmission arrangement. The method of operation of such dual-clutch transmissions is generally known. The one transmission is generally assigned the uneven gearspeeds and the other sub-transmission the even gearspeeds in this context. When driving in a gearspeed via one of the sub-transmissions, a target gearspeed can be preselected in the other sub-transmission. A gear change can then be brought about by overlapping activation of the two friction clutches without an interruption in the tractive force.
Such dual-clutch transmissions are suitable, in particular, for implementing a hybrid drivetrain.
Whereas in conventional drivetrains an electric machine which is designed to make driving power available is arranged in the region of an output of the internal combustion engine, in a dual-clutch transmission it is preferred to connect an electric machine to an input of one of the sub-transmissions. The connection can be made here via a further clutch in such a way that the electric machine can be decoupled from the rest of the drivetrain. However, for cost reasons it is also generally preferred if the electric machine is permanently connected to the input of the one sub-transmission.
In this embodiment, when the friction clutch which is assigned to this sub-transmission is opened, it is generally possible to establish a purely electric driving mode via the gearspeeds of this sub-transmission. In the purely electric method of operation of the hybrid drivetrain, an interruption in the tractive force occurs when there are gear changes.
Of course, such a drivetrain can also be designed for a purely internal combustion engine method of operation in which the electric machine is either decoupled or else idles. Finally, with such a drivetrain it is also possible to establish a hybrid driving mode in which driving power is made available both by the internal combustion engine and by the electric machine.
Finally, with such a drivetrain it is also possible to implement further hybrid functions such as, for example, starting of the internal combustion engine by means of the electric machine, recuperation in an overrun mode of the drivetrain etc.